I bought EGR Valve & Catalytic Converter for 2002 Pontiac Grand Prix GT 3.8L with 225k on Friday, Saturday I had it installed, I should of done the EGR myself just I'm not good with those things & didn't know if I replaced the EGR before the Catalytic Converter if that would mess anything up one before the other as I don't want to be stranded. Only thing is after those 2 things were replaced it still runs like crap. Suggestions? I've asked around. I've been told to get it hooked up to a computer. I contacted another mechanic in MN & he told me take the throttle body off & clean well & then replace.???

175

Asked by Oct 29, 2012 at 09:53 AM about the 2002 Pontiac Grand Prix GT Coupe

Question type: Maintenance & Repair

I bought EGR Valve & Catalytic Converter for 2002 Pontiac Grand Prix GT 3.8L with 225k on Friday, Saturday I had it installed, I should of done the EGR myself just I'm not good with those things & didn't know if I replaced the EGR before the Catalytic Converter if that would mess anything up one before the other as I don't want to be stranded.  Only thing is after those 2 things were replaced it still runs like crap.  Suggestions?  I've asked around.  I've been told to get it hooked up to a computer.  I contacted another mechanic in MN & he told me take the throttle body off & clean well & then replace.???

8 Answers

2,785

it has 225k miles......

2 out of 2 people think this is helpful.
8,355

you can continue to throw parts, or guess....i'd go with technology, is this the same 3.8 that i answered a question about a couple weeks ago? and are there any indicators on, lights on the dash, check engine, any at all?

217,195

Right, what are the issues that you have?

4,405

is your mass airflow sensor clean, a dirty one will affect the way it runs but not nessecarily set a code.

1 out of 1 people think this is helpful.
175

P1404/P0420 before EGR Valve & Catalytic Converter replaced, now no lights on dash other than abs which is disconnected. It only lunges/revs when I drive up hill, slow down then speed up again(4 roundabouts on way home). Where is the mass airflow sensor? Would I be able to clean or replace mass airflow sensor? Would it be the throttle body? Yes this is the same 3.8L I was asking questions about a week.

12,295

Get your car linked to a dynamic engine monitor by an experienced mechanic. This will give you live feedback. As Robert stated above mass air flow definitely a possibility......Mass air flow sensors are not very expensive. They are very delicate careful when installing....

1 out of 1 people think this is helpful.
Best Answer
4,405

It is on your intake by the filter. unplug it, remove the two screws, there is a little sensor on it held in the airstream that when it gets dirty it insulates is giving the pcm wrong readings about the actual air intake and in turn not giving the engine proper amount of fuel for the amount of air coming in. if it was malfunctioning it would set a code but being dirty it's still working just not accurate. clean off the resistors in the sensor you can use brake clean or you can also get maf cleaner made for doint that. if you're careful you can use a q-tip. reinstall and if that's the problem it should run better and probably use less fuel. just by regular maintance like that i got my 97 grand prix up to 36 mpg on the hiway.

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Best Answer
2,785

could be anything, map, mass air sensor, throttle position, sensor idle air motor, or with the mileage you have a combination of one or all, how are the mechanics of the engine , no worn camshaft, no shot fuel injectors......possibilities are endless, and troubleshooting without the proper diagnostic equipment is a shot in dark at best

1 out of 1 people think this is helpful.
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